Imagine trying to survive in oceans around the world, from shallow reefs to the deep sea. For many animals, a habitat like this would be impossible. Yet the octopus, a mollusk from a few centimeters to several meters across, depending on the kind, thrives there, thanks to features that scientists call adaptations: traits that help a living thing survive in its environment.
Consider eight arms covered in suckers: this adaptation grip rocks and pry open shells. Equally important is a cloud of dark ink it can squirt, which hides it while it escapes from predators. Without these traits, the octopus would struggle to last a single season.
As a carnivore, the octopus is an animal that eats other animals; it depends on crabs, shrimp and clams. Its behavior matters as much as its body: it squeezes its soft, boneless body through tiny cracks to hide. Behaviors like this are adaptations too, even though you cannot see them in a photograph.
The next generation faces the same challenges. Young octopus, called hatchlings, depend on their surroundings and on adult care. A mother octopus guards her eggs for weeks and does not leave them, even to eat.
Perhaps most remarkable of all: an octopus has three hearts and blue blood. Facts like this remind us that every animal's body tells a story about the place it lives.